1. Field of the Invention
This invention relates to a shutter for the head access window in the housing for a disk-based memory medium, and more specifically to a surface hardening coating and method for forming such coating on an edge of the shutter.
2. Description of the Prior Art
Shutters are employed over the head access window in the housings of data storage devices which include, but are not limited to "computer microdisks" and "optical disks" (as certain of such storage devices are referred to in the industry) that are used in a wide range of computers and audio/visual devices. The disc-shaped memory medium may include magnetic or optical materials, and is contained within a protective outer shell or housing that includes a head access window and a protective shutter over the window. The housing is configured to slide into a disk drive which comprises a mechanism for opening the shutter and a transducer (the drive head) for reading and/or writing to the disk based memory medium. The mechanism for opening the shutter typically includes a steel pin that is arranged to engage the edge of both legs of the shutter to open the head access window against resilient bias of the shutter toward normally-closed position. The shutter is slidably mounted over the head access window in the housing to protect the disk-shaped memory medium from dust and foreign objects that would otherwise enter through the head access window in the housing. When the housing with the memory medium therein is inserted into the disk drive, the shutter is engaged by a mechanism that slides the shutter to open the head access window and expose the memory medium to a read and/or write transducer. The action of the shutter-opening pin involves an initial impact followed by a pushing and sliding motion on an edge of the shutter to overcome the resilient bias that retains the shutter in normally closed position.
The shutters are commonly formed of stainless steel, which is adequately resistant to wear from contact with the shutter-opening mechanism, but more expensive to use than softer, lower cost metals such as aluminum alloys. However, shutters formed of aluminum alloys commonly deform and abrade at the point of contact with the shutter-opening mechanism after repeated insertions into the disk drive, thereby releasing metal debris. In addition, the deformed shutter abrades the housing which is commonly formed of plastic, thereby releasing plastic debris. The metal and plastic debris will collect on the housing and can contaminate the disk-shaped memory medium contained within the housing to defeat the purpose of the protective housing and shutter.